We wish to understand and describe in molecular detail the mechanisms of transcription, replication, and packaging of the double-stranded RNA chromosomes of bacterial virus phi 6. Infectious phi 6 particles inject into their host, Pseudomonas phaseolicola, three segments of double-stranded RNA along with RNA polymerase. In the infected cell, each segment is transcribed to produce single-stranded RNA and is replicated to produce several hundred progeny double-stranded RNA molecules. Packaging requires assembly of one of each of the three segments around a protein core followed by addition of a coat and a lipid-containing envelope. Proteins must recognize RNA sequences and/or structures at three stages: initiation of transcription, initiation of replication, and assembly of the core. We shall attempt to purify the relevant proteins, to determine the relevant nucleotide sequences and/or structures, and eventually to discover what features of each govern their interaction. This work will exploit a set of temperature sensitive mutants already characterized, some of which are defective in either transcription or replication at high temperature.